In the seats of various transportation means including automobiles, a seat belt device is attached thereto in order to restrain an occupant with a seat belt to suppress inertial movement in an emergency situation such as in the event of collisions, in which a higher deceleration than a normal traveling condition is applied to a vehicle. Such a seat belt device generally includes a tongue supported by a seat belt and a buckle which is fixed to a vehicle body side so that the tongue is inserted therein and latched thereto in order to allow an occupant to easily buckle the seat belt.
A widely known type of buckles used in conventional seat belt devices includes at least a latch member that enters into a latching hole for a tongue to be latched to the tongue when the tongue is inserted, a latch member locking member that moves with biasing force of a spring to lock the latch member at a latching position of the tongue when the latch member is latched to the tongue, a release operating member that releases the lock state of the latch member locked by the latch member locking member and removes the latch member from the latching hole for the tongue to release the latch state between the latch member and the tongue, and an ejector that presses the tongue in a direction in which the tongue is separated from the buckle when the release operating member releases the latch state between the latch member and the tongue (for example, see JP-U-HOS-015813).
In a seat belt device having such a type of a buckle, when the seat belt is buckled to an occupant, the tongue is inserted into the buckle and the latch member is latched to the tongue whereby the tongue is latched to the buckle. As a result, since the seat belt is buckled to the occupant and the occupant is restrained to the seat belt in the emergency situation, the inertial movement of the occupant is suppressed. Moreover, when the seat belt is unbuckled from the occupant, the release operating member is pressed by the occupant whereby the latch state between the latch member and the tongue is released.
As an example of such a buckle, a so-called illuminated buckle having a light source such as LED in the buckle so that an occupant can easily perceive a tongue insertion hole in the night hours is known. In the illuminated buckle, a printed circuit board and an LED as a light source are provided in the buckle and are fixed so as to correspond to both side portions of the tongue insertion hole.
In such a conventional illuminated buckle device, when an occupant sits on a seat, for example, the LED of the buckle device is operated to emit light to illuminate an insertion hole in a buckle body with the aid of a light guide, and the occupant can easily perceive the insertion hole.